| 摘要 |
<p>1512275 Magnesia-phosphate cements W R GRACE & CO 21 Nov 1975 [21 Nov 1974] 47995/75 Heading C1H A cement composition contains (1) magnesium oxide, (2) a phosphate component reactive therewith comprising one or more ammonium phosphate(s) and (3) one or more oxy-boron compound(s) selected from oxyacids of boron, their salts and their esters and/or one or more boron compounds which form the oxyboron compound(s) on contact with water, in an amount sufficient to retard the normal setting time of the magnesium oxide-ammonium phosphate cement in water. The phosphate component may contain a less reactive component, e.g. sodium or potassium phosphate. Fillers, e.g. silica, sand, alumina, zircon, zirconia, raw dolomite, chrome ore, limestone, clinker, vermiculite, perlite and fly ash may be present.</p> |
